US2754365A

US2754365A - Acoustical tone control for wearable hearing aids

Info

Publication number: US2754365A
Application number: US309584A
Authority: US
Inventors: Warren R Walters
Original assignee: MAICO Co Inc
Current assignee: MAICO Co Inc; MAICO COMPANY Inc
Priority date: 1952-09-15
Filing date: 1952-09-15
Publication date: 1956-07-10
Anticipated expiration: 1973-07-10

Description

July 10, 1956 w. R. WALTERS 2,754,365

ACOUSTICAL TONE CONTROL FOR WEARABLE HEARING AIDS Filed Sept. 15. 1952 2 Sheets-Sheet 1 INVENTOR.

War/v03 Wefiaj /7 BY July 10, 1956 w. R. WALTERS ACOUSTICAL TONE CONTROL FOR WEARABLE HEARING AIDS Filed Sept. 15, 1952 2 Sheets-Sheet 2 0 u z z W FRf'QUE/YCY //Y CR6.

MICROPHONE F4? Mala IN VEN TOR.

wa e/Z2 m 20 BY WW1 nited States Patent 4 ACOUSTICAL TONE CONTROL F QR WEARABLE HEARING AIDS Warren R. Walters, Natiek, Mass, assignor to The Maico Company, incorporated, Minneapolis, Minn., a corporation of Minnesota Application September 15, 1952, Serial No. M9584 Claims. (Cl. 179-107) My present invention relates to improvements in wearable hearing aids, and more particularly to that type of hearing aid structure comprising an air conduction type audio reproducer or receiver located remotely from the wearers ear and is connected to an auditory canal of the car by a flexible sound conduit or tube and a suitable ear piece or coupling. In hearing aids of this general character, the quality of the sound presented at the wearers ear is often impaired as a result of frequency discrimination, which takes place during transmission of the sound waves through the flexible sound delivery conduit tube, and which most usually appears at the car as an overemphasis of those frequencies at the lower portion of the speech sound spectrum. The magnitude of this apparent over-ernphasis of low frequencies depends largely upon the physical characteristics of the flexible sound conduit and the length of the sound conduit, both of which are widely variable, and the latter of which is usually adjusted to suit the requirements of each user. From this it will be seen that the variable factors controlling the degree of frequency discrimination taking place within the flexible sound conduit make it difficult and, in most cases, impractical to correct the frequency response electrically within the amplifier or any point ahead of the reproducer.

It is, therefore, an object of the instant invention to provide a simple and highly efficient means for correcting the frequency response of the acoustical portion of the hearing aid to compensate for frequency discrimination which takes place during transmission of sound waves through the flexible sound delivery conduit from the reproducer or receiver to the auditory canal of the user. in accordance with the invention, I accomplish this objective inexpensively and very satisfactorily by providing one or more restricted vent passages to atmosphere from the acoustical sound delivery system at a place therein ahead of the flexible sound delivery conduit. in practice, it is found that venting of the acoustical system to atmosphere produces a frequency discrimination in the direction tending to correct for the frequency discrimination which takes place within the flexible sound delivery conduit, and that the degree of such corrective frequency discrimination can be widely varied by merely varying the total cross-section area of the venting passage or passages. In practice, I have found that locating such tone control venting passage or passages ahead of the sound delivery conduit, rather than at or adjacent the delivery end thereof, results in improved clarity of the sounds delivered to the ear. It is believed that this improvement is due to the fact that the tendency to produce types of distortion other than frequency discrimination is reduced by eliminating from the acoustical system part of the unwanted sound before introduction of the sound into the flexible conduit.

in the preferred embodiment of the invention illustrated, the acoustical tone control comprises a plurality of restricted vent passages and a manually-operative valve mechanism for selectively controlling the opening and 2,754,365 Patented July 10, 1956 ice closing of said passages. In fact, in the preferred structure illustrated, the flexible sound delivery conduit is coupled to the audio reproducer or receiver by a coupling head having an internal cavity in sealed communication with the interior of the speaker or reproducer casing, and which coupling head defines the said tone control vent apertures and carries the valve mechanism for manually controlling said passages.

The above and other highly important objects and advantages of the invention will be made apparent from the following specification, claims and appended drawings.

In the accompanying drawings, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. l is a view in elevation, with some parts broken away and some parts shown in section, of a wearable electronic hearing aid incorporating a preferred embodiment of the invention, and showing the same in operative relation to the ear of a hard of hearing person wearing the instrument;

Figs. 2, 3 and 4 are greatly enlarged views in side elevation, with some parts broken away, of the reproducer and associated tone control valve mechanism of Fig. 1, said views respectively showing the tone control valve in different adjusted positions;

Fig. 5 is a transverse sectional view, with some parts on the section line shown in full and some parts broken away, taken on the line 55 of Fig. 3;

Fig. 6 is a detail sectional View, taken on the line 6-6 of Fig. 4, with some parts on the section line shown in full;

Fig. 7 is a diagrammatic view graphically illustrating the frequency response of the hearing aid at the users ear in three different positions of the tone control valve mechanism; and

Fig. 8 is a diagrammatic view of the main hearing aid components, showing in block-type diagram the amplifier and microphone contained within the hearing aid casing shown at the bottom of Fig. 1.

In Fig. l, the ear of a hard of hearing person wearing a hearing aid equipped with the invention is indicated by 1 and part of the clothing of such person is indicated by 2. The main casing or housing of the wearable hearing aid is indicated by full lines at 3 in Fig. l and by correspondingly-identified dotted lines in Fig. 8. This main casing or housing is adapted to be worn in a pocket of the user, or suitably attached to the clothing of the user by other well-known means not illustrated and contains the usual microphone 4 and electronic audio power amplifier 5, shown in block diagram in Fig. 87 As shown in Fig. 8, the electrical output end of the microphone 4 is connected to the input of the amplifier 5 by a pair of leads 6. The electrical output of the amplifier 5 is connected by a pair of flexible lead wires 7 to the remotelylocated audio frequency reproducer or receiver, indicated as an entirety by 8.

As illustrated, the audio reproducer S is of the conventional, miniature, electro-magnetically operated variety, commonly used in the hearing aid industry and comprises telescopically engaged inner and outer casing or housing sections 9 and 10, respectively, containing the usual magnetically responsive diaphragm i1 and electromagnet diaphragm actuating structure 12. In Fig. 5, the winding of the electromagnetic structure 12 is indicated by 13, and it may be assumed that the leads 7 from the amplifier 5 are connected thereto. The reproducer housing section 10 and diaphragm 11 cooperatively define a sound chamber 14 and the said housing section 10 defines a tubular coupling nipple 15 providing a sound outlet passage 16 from the sound chamber 14. Preferably, and as illustrated, the coupling nipple 15 is reduced in g diameter inwardly of its outer end to provide a lock ring receiving channel 17 (see Figs. 5 and 6).

The acoustical output of the reproducer or receiver 8 is connected to the auditory canal of one of the users ears 1 through the sound outlet passage 16, a flexible sound delivery tube or conduit 18, a coupling head 19, and an ear piece coupling 2 The ear piece or coupling is of the conventional moulded type and defines a coupling nipple 21 that is adapted to be inserted into the auditory canal of the associated ear to make sealed communication therewith. The flexible sound conduit 8 may be of various different materials, but is usually formed of a suitable plastic material having suitable flexibility and color characteristics. The coupling head 19 is bored to provide an internal cavity 22, which receives the coupling nipple 15 (see Figs. 5 and 6) and defines an extension of the sound chamber 14 of the reproducer 8. The coupling head 19 is detachably locked on the coupling nippl 15 by means of a conventional split lock ring 23, contained within a channel 24 of the coupling head 19 and seated in the channel 17 of the coupling nipple 15. The internal cavity or chamber 22 of the coupling head 19 is sealed from atmosphere by a resilient gasket 24 interposed between the adjacent flat surfaces of the coupling head 19 and reproducer housing section 10. A sound outlet passage 25 is provided from the cavity or chamber 22 of the coupling head 19 by a coupling nipple 26, which is telescopically fitted to the adjacent end of the flexible sound outlet conduit 18, as best shown in Fig. 1 By further reference to Fig. 1, it will be seen that the reproducer or receiver 8 is adapted to be supported from the Wearers clothing 2 by attached chain links or the like 27 and a pin or the like 28.

In the preferred embodiment of the invention illustrated, the acoustical tone control comprises two vent passages or orifices through the coupling head 19 from its internal cavity or sound chamber 22, respectively indicated by 29 and 3t), and a manually-operated valve 31 for controlling the said

vent passages

29 and 30. The valve 31 is a disc-like elementmounted on the flat outer face of the coupling head 19 by means of a headed mounting and locking screw 32 disposed coaxially thereof and the head 19 and having threaded engagement with the latter. The vent orifices or

passages

29 and 30 underlie the valve disc 31 and are disposed in circumferentiallyspaced relation about the axis of the valve disc 31. The valve disc 31 is provided with a pair of circumferentiallyspaced passages, respectively indicated by 33 and 34, arranged for cooperative registration with the vent passages 29 and 31). When the screw 32 is tight, the valve disc 33 is locked against accidental movement and the adjacent faces thereof and the head 19 make air-tight sealing engagement.

By reference to Figs. 1, 2, 3 and 4, it will be seen that the valve disc 31 is provided with a position-indicating arrow for cooperation with position-indicating

numerals

1, 2, and 3 arranged in circumferentially-spaced relation on the outer face of the coupling head 19. By reference to Fig. 2, it will be noted that when the valve disc is positioned with its arrow 35 opposite the numeral 1 of the coupling head, the valve disc orifices or passages 33 and 34 are both out of registration with the coupling head or

vent passages

29 and 30, so that the coupling head pasages 23 and 30 are both closed. By reference to Fig. 3, it will be seen that when the valve disc arrow 35 is in registration with the numeral 2 of the coupling head, the valve disc orifice 34 is in registration with the coupling head vent passage 29, while the coupling head vent passage 30 remains closed. By reference to Fig. 4, it will be seen that when theval've disc 31 is positioned with its arrow 35 opposite the numeral 3 of the coupling head, the valve disc orifice'34 is in'registration with the coupling head orifice 30 and the valvediscorifice 33 is in registration'with the coupling vent passage or orifice 29: In each ofthese'threedifferent positions 'of the tone 4- control valve disc 31, shown respectively in Figs. 2, 3 and 4, a tone quality or response characteristic of the sound presented to the users ear will be different, as clearly illustrated graphically in Fig. 7.

By reference to Fig. 7, horizontal lines on the graph represent sound pressure response characteristics in decibels (db) and vertical lines indicate different frequencies Within the speech sound spectrum in cycles per second (C. P. S On this graph of Fig. 7, the full line curve marked Position 1, indicates the response characteristic at the users ear of the hearing aid when the valve disc 31 is in position 1, as indicated in Fig. 2; the broken line curve marked Position 2, indicates the response characteristic of the hearing aid when the tone control valve disc 31 is in position 2, as shown in Fig. 3; and the dotted line curve marked Position 3 indicates the response characteristic of the hearing aid when the valve disc 31 is in position 3, as shown in Fig. 4. Otherwise stated, curve position 1 illustrates the acoustical response when both of the

vent passages

29 and 30 are closed; curve position 2 illustrates the acoustical response characteristic of the instrument when the vent passage 29 is open and the vent passage 30 is closed; and curve position 3 illustrates the acoustical response of the instrument when the

vent passages

29 and 30 are both fully opened. Of course, it will be understood that response characteristics intermediate those shown may be obtained by partially opening or closing one or both of the

passages

29 and 30. It will be understood that these response characteristics are representative of What may be expected when the electrical output of the amplifier is substantially uniform throughout the speech sound spectrum, and that the apparent over-emphasis of the low frequency portion of the spectrum between the cycles per second and about 700 cycles per second is due to frequency discrimination in the acoustical portion of the system represented by the flexible sound delivery condit 18. Of course, this over-emphasis of low frequencies will prove very unnatural and undesirable to many hearing aid users, but may prove desirable to some users whose hearing is particularly deficient in the low frequency portion of the speech frequency spectrum. Most hard of hearing persons will find the sound characteristics most desirable when the tone control valve disc 31 is in one of

positions

2 or 3, which produce a progressive attenuation of the otherwise over-emphasized low frequencies, and produce a much closer approach to a uniform amplification of all frequencies within the speech sound spectrum. It will, of course, be obvious that greater low frequency attenuation may be provided by further increasing the total area of the vent passage or passages.

My invention has been thoroughly tested and found to be entirely adequate for the accomplishment of the objectives set forth; and, while I have shown a preferred embodiment of my invention, it will be understood that the same is capable of modification without departure from the spirit and scope of the invention as defined in the claims.

What I claim is:

1. An electrically-operated audio reproducer for use as part of a Wearable hearing aid and adapted to be worn by a hard of hearing person in a position remote from an auditory canal of such person, said reproducer being of the air conduction type and comprising a casing defining the sound outlet passage, a coupling head detachably applied to the exterior of the reproducer casing and having an internal cavity in sealed communication with the outlet passage of the reproducer, a flexible sound delivery conduit leading from the coupling head and being in sealed communication with the internal cavity thereof, the extended end of said flexible sound conduit being adapted to be coupled to the auditory canal of a person wearing the hearing aid, and means for' attenuating 'low frequency sound wavesdelivered by the reproducer to the flexible sound conduit to'conipensate for frequency discrimination within the flexible sound delivery conduit, said means comprising a restricted venting passage from the internal cavity of the coupling head to atmosphere.

2. An electrically-operated audio reproducer for use as part of a wearable hearing aid and adapted to be worn by a hard of hearing person in a position remote from an auditory canal of such person, said reproducer being of the air conduction type and comprising a casing defining the sound outlet passage, a coupling head detachably applied to the exterior of the reproducer casing and having an internal cavity in sealed communication with the outlet passage of the reproducer, a flexible sound delivery conduit leading from the coupling head and being in sealed communication with the internal cavity thereof, the extended end of said flexible sound conduit being adapted to be coupled to the auditory canal of a person wearing the hearing aid, and means for attenuating low frequency sound waves delivered by the reproducer to the flexible sound conduit to compensate for frequency discrimination Within the flexible sound delivery conduit, said means comprising a restricted venting passage from the internal cavity of the coupling head to atmosphere, and a manually-operated valve for opening and closing said passage.

3. An electrically-operated audio reproducer for use as part of a wearable hearing aid and adapted to be worn by a hard of hearing person in a position remote from an auditory canal of such person, said reproducer being of the air conduction type and comprising a casing defining he sound outlet passage, a coupling head detachably applied to the exterior of the reproducer casing and having an internal cavity in sealed communication with the outlet passage of the reproducer, a flexible sound delivery conduit leading from the coupling head and being in sealed communication with the internal cavity thereof, the extended end of said flexible sound conduit being adapted to be coupled to the auditory canal of a person wearing the hearing aid, and means for attenuating low frequency sound waves delivered by the reproducer to the flexible sound conduit to compensate for frequency discrimination within the flexible sound delivery conduit, said means comprising a plurality of restricted venting passages from the internal cavity of the coupling head to atmosphere, and a manuallyoperated valve associated with the coupling head for selectively opening and closing said passages.

4. An electrically operated audio reproducer for use as part of a wearable hearing aid and adapted to be worn by a hard of hearing person in a position remote from an auditory canal of such person, said reproducer being of the air conduction type and comprising an electromagnetically operated diaphragm, a casing structure enclosing the diaphragm and defining a sound chamber in communication with one side of the diaphragm, and a sound outlet passage leading from said chamber, a flexible sound delivery conduit coupled to said chamber through said passage, the extended end of said flexible sound conduit being adapted to be coupled to the auditory canal of a person wearing the hearing aid, and means for attenuating the low frequency sound waves delivered by the reproducer to the flexible sound conduit to compensate for frequency distortion within the flexible sound delivery conduit, said means comprising a restricted venting passage from said sound chamber to atmosphere.

5. An electrically operated audio reproducer for use as part of a wearable hearing aid and adapted to be worn by a hard of hearing person in a position remote from an auditory canal of such person, said reproducer being of the air conduction type and comprising an electromagnetically operated diaphragm, a casing structure enclosing the diaphragm and defining a sound chamber in communication with one side of the diaphragm, and a sound outlet passage leading from said chamber, a flexible sound delivery conduit coupled to said chamber through said passage, the extended end of said flexible sound conduit being adapted to be coupled to the auditory canal of a person wearing the hearing aid, means for attenuating the low frequency sound waves delivered by the reproducer to the flexible sound conduit to compensate for frequency distortion within the flexible sound delivery conduit, said means comprising a restricted venting passage from said sound chamber to atmosphere, and a manually operated valve for opening and closing said restricted venting passage.

References Cited in the file of this patent UNITED STATES PATENTS 1,915,358 Giles June 27, 1933 2,215,585 Huenlich Sept. 24, 1940 2,271,467 Smithline Jan. 27, 1942 2,505,124 Lepeschkin Apr. 25, 1950 2,506,981 Weaver et a1 May 9, 1950 2,541,164 Huenlich Feb. 13, 1951